1. Field of the Invention
This invention relates to growing fish or crustaceans, and, more particularly, to feeding the fish or crustacean with a particulate foodstuff composition to increase their conversion, growth and survival rates.
2. Description of the Prior Art
Farm fishing of fish and crustaceans is a world-wide business activity. It is customary to manufacture fish foods used in farm fishing in the form of discrete granules or pellets so as to facilitate handling of the foods, reduce dust and wastage, and to control the food particle size and density. For the manufacture of such fish foods, it has been conventional for many years to incorporate a polymeric binder material as a part of the composition.
Lignosulphonate is widely used as a binder, notably in the pelleting of start feeds, that is, for very young, fast growing fish. Alginates and guar gum also are used as binders for this purpose, generally in moist feeds for larger fish. Although these binder materials are generally regarded as benign, it has been known for some years that they do interfere to some extent with digestion of the foodstuffs by the fish. This limitation, however, has been accepted for the sake of manufacturing the feeds in particulate form.
Starch is also used as a binder in extruded fish feeds for larger fish, but it is less effective as a binder so that a substantial amount is required, generally at levels of about 20%. Such high levels of starch alters the natural diet of the fish.
Accordingly, it is an object of this invention to provide an improved method of growing fish or crustaceans at increased conversion, growth and survival rates.
Another object herein is to provide a method of feeding the fish or crustacean with a particulate foodstuff composition to bind said foodstuff in the form of a pellet of sufficient strength and hardness in water to enable the fish or crustaceans to feed effectively on said composition during both their early and late growth stages.